Method of and apparatus for making concentrated filaments



Aug. 27 1929., FEHSE 1,726 480 METHOD OF AND APPARATUS FOR MAKING CONCENTRATED FILAMENTS Filed May 7Q 1927 Fig.8;

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Inventor: Adolf Fehse Ha: Attorney.

Patented Aug,: 27, 1929.

UNITED STATES 1,726,480 PATENT" OFFICE.

ADOLF FEHSE, 0F BERLIN, GERMANY, ASSIGNOR TO GEN ERAL ELECTRIC COMPANY, A

' CORPORATION OF NEW YORK.

METHOD or AND APPARATUS non MAKING CONGENTBATED FILAMENTS.

Application filed May 7, 1927, Serial No. 189,506, and in GermanyJuly 10, 1926.

In electric incandescent lamps for certain uses, such as projection, it is frequently desirable that the light source be very concentrated or compact.

The degree of concentration of the filament a millimeter, may suflice to bring into contact the coils or other parts of the filament which are close together and thus develop a short circuit.

One object of the invention is to provide wire or ribbon filaments which will safely carry heavy currentsand which are highly concentrated- Another object is to provide such concentrated filaments which consist of several closely adjacent coils or even of doubly wound coils. To this end the manufacture of the filament is so conducted that a coiled filament of wire or ribbon, oreither of them, wound into ahelix, is formed over acofre which determines the final shape of the filament, and is then clamped with the core in an enclosin box or filament envelope, and therein nally heated so high that the formed filament no longer has any interior stresses and thus isv stable and has no tendency to spring or distort. If the filament is oftungsten, the heating of the box and the filament totally enclosed init is carried tosomewhat over 1300 (3.! In order tobring all parts of the formed filament to as nearly as possible the same temperature the filament is advantageously heated indirectly by heat radiation and not directly by the assage of current through it. To this en the filament envelope and the core are placed in a mufile furmice and left there-until both the core and the filament envelope reach the required high temperature. By this invention electric incandescent lamps suitable for projection purposes may be made having filaments with sections very close to one another and doubly coiled into double helices, and may be operated to consume 1000 watts at line voltages of 110 01 even 220 volts. Hitherto 1000 watts incandescent lamps with concentrated filaments and suitable forprojection purposes could be made only 15 to 30 volts.

The invention will best be understood in connection with the accompanyin drawings, in wh ch is shown one example ot a filament made in accordance with this invention and onemethod of practicing the invention, and in wlnch'Flg. 1 is an elevation. of a lamp mount having a concentrated filament made in acfor low voltages, such as cordance with this invention; Fig. 2 is a crosssectionof the filamentshown in Fig. 1; Fig. 3 s a v ew of the filament before it is shaped; Fig. 4 1s a side view of the core with a part of the filament in place on it; Fig. 5 is a top v ew of Fig. 4; Fig. 6 is an end view of Fig. 4; Fig. 71s a cross-section of the filament'heatmg box contalning the formed filament on the core; and Flg. 8 is a longitudinal section through Fig. 7.

As one example of the invention the manufacture of afilament suitable for projection purposes and of the form shown in elevation in Fig. 1 and in plan in Fig. 2 will be described. This particular filament consists of SIX parallel columns or straight sections very close together and made of tungsten Wire a coiled once or even twice into a helix. The t-WPStI'aIght end portions 6 of the helically coiled filament are fastenedto leads 0 which are connected to leading-in wires d. The bends 6 between the sixcolumns or filament sections are suspended in anchors 7. Both the anchors f'and the leads a are supported by and sealed into the stem 9. Y

The manufacture of this filament shown in Figs. 1 and 2 begins with the double coiled straight filament shown in Fig. 3 on a larger scale. The double coiled sections a of the filament form in the finished filament the columns or closely adjoining sections, and the single coiled sections e form the upper and the lower bends of the filament. Theends b of the coiled filament are used, as shown by Fig. 1, as connections to the leads 0. This coiled filament, made on the usual wire coiling machine, is first shaped by being placed on the core shown on an enlarged scale in three different views in Figs. 4 to 6. The core is an oblong rectangular block of refractory material, advantageously tungsten, provided on both sides with grooves 'i to receive the closely coiled sections of the coiled filament. In the tungsten.

upper edge of the block 72. are two grooves 70 to receive the two coiled ends 6 which are to be fastened to the leads 0. the coiled filament extend along the upper and the lower edges ofthe block. In order that these bends may also be set in their positions, correspondingly smaller grooves 011. are provided in the upper and lower edges of the block it for joining the adjacent ends of the grooves 1 for the straight sections a of the filament. Placing the coiled filament in the grooves of thecore accurately determines the final shape ofthe filament.

The filament wound on the core is then laid on the bottom of a boat or trough n, Figs. 7, 8 and 9, which also consists of a refractory material, preferably tungsten. Over the wound core it there is placed a cup or core 0 which fits over the wound core snugly enough to prevent movement of the filament in the grooves and also fills the boat n. This cover likewise consists of a refractory material, preferably The cover is pressed down onto the boat by a pin bolt 79 to fit tightly over the wound core h. The filament on its core is thus clamped in the filament envelope formed by the boat and the cover and held immovably in place. The boat with the enclosed core clamped in it is then put into a furnace, such as a mufile furnace, and left there until the filament is sufficiently heated. After the boat is taken out and cooled the cover 0 can be raised and the filament removed from 'its core h. The shape given it by the core and the cover 0 isretained by it after being put into the lamp and after thedamp has been used.

What I claim as new and desire to secure The bends e of by Letters Patent of the United States, is 1. Apparatus for shaping a metal filament into a concentrated form comprising a refractory boat, a cup-shaped cover which fits into said boat with its edges on the bottom of the boat, a core which fits into said cover, and a pin cooperating with said boat to press said cover firmly to the bottom of the boat.

2. Apparatus for shaping a coiledmetal filament into a concentrated form, comprising an oblong core having parallel grooves on its sides to receive and position straight sections of said coiled filament, and grooves in its edges to join the adjacent ends of said parallel grooves and to-receive intermediate portions of said filament and to position them between said straight sections, a cover which fits snugly over said core and holds the filament in place in said grooves, and means for holding said cover in place during heating of said core and cover. 3. Apparatus forshaping a coiled filament into concentrated form comprising an oblong core having on the sides parallel grooves to hold straight coiled sections of the filament snugly side by side, smaller transverse grooves joining'the ends of the side grooves to receive the intermediate bends of the filament, and a cover to fit over the core and filament thereon to hold the filament in said grooves.

4. Apparatus for shaping a coiled filament into concentrated form comprising an oblong core having on its sides grooves of a depth no greater than the radius of the turns of the a'cover to fit over said core and engage the coil in said grooves throughout its length.

In witness whereof, I have hereunto set my hand this 21st day of April 1927.

ADOLF FEHSE.

coils and shaped to fit said coils snugly, and 

